The Existence of Solutions of （k, n - k） Conjugate Boundary Value Problems in Banach Spaces

In this paper,by use of the Schauder fixed-point theorem,the existence of solution of (k,n-k) Conjugate boundary value problems in Banach spaces is investigated.     

Fission fragment mass yields of Th to Rf even-even nuclei

Fission properties of the actinide nuclei are deduced from theoretical analysis. We investigate potential energy surfaces and fission barriers and predict the fission fragment mass yields of actinide isotopes. The results are compared with experimental data where available. The calculations were performed in the macroscopic-microscopic approximation with the Lublin-Strasbourg Drop (LSD) for the macroscopic part, and the microscopic energy corrections were evaluated in the Yukawa-folded potential. The Fourier nuclear shape parametrization is used to describe the nuclear shape, including the non-axial degree of freedom. The fission fragment mass yields of the nuclei considered are evaluated within a 3D collective model using the Born-Oppenheimer approximation.     

Structural,magnetic, and dielectric properties of Ni–Zn ferrite and Bi_2O_3 nanocomposites prepared by the sol-gel method

Ni–Zn ferrite and Bi_2O_3 composites were developed by the sol-gel method. The structural, magnetic, and dielectric properties were studied for all the prepared samples. X-ray diffraction(XRD) was performed to study the crystal structure.The results of field emission scanning electron microscopy(FE-SEM) showed that the addition of Bi_2O_3 can increase the grain size of the Ni–Zn ferrite. Magnetic properties were analyzed by a hysteresis loop test and it was found that the saturation magnetization and coercivity decreased with the increase of Bi_2O_3 ratio. In addition, the dielectric properties of the Ni–Zn ferrite were also improved with the addition of Bi_2O_3.     

微波加热合成多孔花状结构的纳米α-Bi_2O_3

<正>金属氧化物如氧化钛、氧化锌、氧化铜、氧化铁和氧化铋等是一类重要的半导体材料,它们在磁存储介质、太阳能转换、电子器件和催化等领域里有着广泛的应用,因此其纳米粉体的制备及性能研究吸引了众多的科学工作者。     

Controlled Synthesis of Sea-urchin-like ZnO Nanomaterials with the Aid of Ethylene Glycol Using a Solvothermal Method

Sea-urchin-like ZnO nanomaterials were successfully synthesized by decomposition of zinc acetate precursor in the presence of sodium hydroxide and ethylene glycol(EG) in an ethanol solution using a solvothermal method at 180 ℃ for 12 h.The crystalline phase and morphology of the resultant nanomaterials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),selected-area electronic diffraction(SAED) and high-resolution electron microscopy(HRTEM).Interestingly,the sizes and prod length of the samples can be easily tuned by changing the amount of directing agent EG and keeping other reaction conditions unchangeable.On the basis of our experimental outcomes,EG-controlled-nucleation-growth formation mechanism was proposed to correspond for the sea-urchin-like ZnO growth processes.And the photoluminescence(PL) spectra of the as-selected samples were measured at room temperature,presenting two emission peaks centered at～388 and 480 nm.     

转基因棉花残体土壤降解特征的红外光谱研究

采用重铬酸钾容量法和红外光谱(FTIR)法分析了转基因抗虫棉花残体降解后的土壤腐殖质组分富里酸(FA)、胡敏酸(HA)和胡敏素(HM)的含量和结构特征.结果表明,棉花残体的降解使土壤各腐殖质组分含量增加,胡敏素的相对含量增加最大,胡敏酸次之,富里酸最小.与相应非转基因对照相比,转Bt基因棉花残体处理土壤各腐殖质组分含量...     

Toluene sensing properties of SnO2-ZnO hollow nanofibers fabricated from single capillary electrospinning

SnO₂-ZnO hollow nanofibers were fabricated through a facile single capillary electrospinning technology. The structure and toluene sensing properties of the hollow fibers were investigated. The results indicated that the fibers possess a hollow structure, a rough porous surface after being annealed at 600 °C and the diameters are in the range of 80-160 nm. A sensor fabricated from these fibers exhibits considerable sensitivity and good stability against toluene at 190 °C, which can be attributed to the special 1D hollow structure and the promoting effect of the SnO₂/ZnO heterojunction. The formation mechanism and toluene sensing mechanism of SnO₂-ZnO hollow nanofibers were also discussed.     

地球章动原因的分析与计算

介绍地球章动的特点,从理论上分析地球章动的主要原因,计算章动常数并给出了地球章动示意图的画法.所计算的章动常数与观测值相差仅2/10 000.     

Maxwell方程离散系统的谱分析

主要考虑有限元离散混合时谐Maxwell方程的鞍点线性方程组的谱分析.理论分析显示在一定的条件下相应系数矩阵的特征值是非常聚集的.     

Acoustic metamaterial with negative density

We fabricated a one-dimensional acoustic metamaterial with negative effective density using an array of very thin elastic membranes. We observed acoustic equivalence of the plasma oscillation at ωc=735 Hz. The metamaterial was opaque in the frequency range from 0 to 735 Hz, and was transparent above 735 Hz. We report direct observation of negative acceleration in this acoustic medium below 735 Hz. The frequency characteristics of the metamaterial have the same form as that of metals with negative permittivity. We also provide a simple theory to explain the experimental results.